2.3 Coagulation System Disorders

Question 1

The APTT is sensitive to a deficiency of which clotting factor?
A. Factor VII
B. Factor X
C. PF3
D. Calcium

Answer 1

B. Factor X

The APTT is sensitive to the deficiency of coagulation factors in the intrinsic pathway (factors XII, XI, IX, and VIII) and the common pathway (factors X, V, II, and I).

Question 2

Which test result would be normal in a patient with dysfibrinogenemia?
A. TT
B. APTT
C. PT
D. Immunologic fibrinogen level

Answer 2

D. Immunologic fibrinogen level

Question 3

A patient with a prolonged PT is given intravenous vitamin K. PT is corrected to normal after 24 hours. Which clinical condition most likely caused these results?
A. Necrotic liver disease
B. Factor X deficiency
C. Fibrinogen deficiency
D. Obstructive jaundice

Answer 3

D. Obstructive jaundice

Obstructive jaundice contributes to coagulation disorders by preventing vitamin K absorption. Vitamin K is a fat soluble and requires bile salts for absorption. Parenteral administration of vitamin K bypasses the bowel, hence the need for bile salts.

Question 4

Which factor deficiency is associated with prolonged PT and APTT?
A. Factor X
B. Factor VIII
C. Factor IX
D. Factor XI

Answer 4

A. Factor X

Factor X, a common pathway factor deficiency, is most likely suspected because both PT and APTT are prolonged. Other causes may include liver disease, vitamin K deficiency, and anticoagulant drugs, such as warfarin and heparin.

Question 5

Prolonged APTT is corrected with factor VIII-deficient plasma but not with factor IX-deficient plasma. Which factor is deficient?
A. Factor V
B. Factor VIII
C. Factor IX
D. Factor X

Answer 5

C. Factor IX

Question 6

Which of the following is a characteristic of classic hemophilia A?
A. Abnormal PLT aggregation
B. Autosomal recessive inheritance
C. Mild to serve bleeding episodes
D. Prolonged PT

Answer 6

C. Mild to serve bleeding episodes

Hemophilia A (factor VIII deficiency ) is characterized by mild to severe bleeding episodes, depending on the concentration of factor VIII: C. Hemophilia A is inherited as a sex-linked disease. PLT aggregation and PT are both normal in hemophilia A.

Question 7

Refer to the following results:
PT= prolonged
APTT = prolonged
PLT count = decreased

Which disorder may be indicated?
A. Factor VIII deficiency
B. von Willebrand disease
C. DIC
D. Factor IX deficiency

Answer 7

C. DIC

In DIC, there is a diffuse intravascular generation of thrombin and fibrin. As a result, clotting factors and PLTs are consumed, resulting in decreased PLT count and increased PT and APTT.

Question 8

Which of the following is a predisposing condition for the development of DIC?
A. Adenocarcinoma
B. Idiopathic thrombocytopenic purpura (ITP)
C. Post transfusion purpura (PTP)
D. Heparin-induced thrombocytopenia (HIT)

Answer 8

A. Adenocarcinoma

Adenocarcinoma can liberate procoagulant (thromboplastic) substances that can activate prothrombin intravascularly. ITP is a thrombocytopenia caused by an autoantibody; PTP is an alloimmune thrombocytopenia caused by transfusion of blood or blood products; HIT results from an antibody to heparin-PF4 complexx causing thrombocytopenia in 1% to 5% of patients who are on heparin therapy. In some affected persons, thrombosis may also occur.

Question 9

Factor XII deficiency is associated with:
A. Bleeding episodes
B. Epistaxis
C. Decreased risk of thrombosis
D. Increased risk of thrombosis

Answer 9

D. Increased risk of thrombosis

Question 10

The following results were obtained on a patient: normal PLT count and function, normal PT, and prolonged APTT. Which of the following disorders is most consistent with these results?
A. Hemophilia A
B. Bernard-Soulier syndrome
C. von Willebrand disease
D. Glanzmann thrombasthenia

Answer 10

A. Hemophilia A

Question 11

The following laboratory results were obtained from a 40-year-old woman: PT= 20 sec; APTT= 50 sec; TT=18 sec. What is the most probable diagnosis?
A. Factor VII deficiency
B. Factor VIII deficiency
C. Factor X deficiency
D. Hypofibrinogenemia

Answer 11

D. Hypofibrinogenemia

Fibrinogen (Factor I) is a clotting protein of the common pathway and is evaluated by TT. In hypofibrinogenemia (fibrinogen concentration less than 100 mg/dL), PT, APTT, and TT are prolonged. In factor VII deficiency, APTT is normal; in factor VIII deficiency, PT is normal; and in factor X deficiency, TT is normal.

Question 12

When performing a factor VIII activity assay, a patient’s plasma is mixed with:
A. Normal patient plasma
B. Factor VIII-deficient plasma
C. Plasma with a high concentration of factor VIII
D. Normal control plasma

Answer 12

B. Factor VIII-deficient plasma

Question 13

The most suitable product for treatment of factor VIII deficiency is:
A. Fresh frozen plasma (FFP)
B. Factor VIII concentrate
C. Prothrombin complex concentrate
D. Factor V Leiden

Answer 13

B. Factor VIII concentrate

Factor VIII concentrate (human or recombinant) is the treatment of choice for patients with factor VIII deficiency. FFP contains factor VIII; however it is no longer used as the primary treatment for factor VIII deficiency. Prothrombin complex concentrate is used to treat patients with factor VIII inhibitor.

Question 14

Which of the following is associated with an abnormal PLT aggregation test result?
A. Factor VIII deficiency
B. Factor VIII inhibitor
C. Lupus anticoagulant
D. Afibrinogenemia

Answer 14

D. Afibrinogenemia

Fibrinogen is a plasma protein that is essential for PLT aggregation as well as fibrin formation. In afibrinogenemia, PLT aggregation is abnormal.

Question 15

Refer to the following results:
PT = normal
APTT = prolonged
PLT count = normal
PLT aggregation to ristocetin = abnormal

Which of the following disorders may be indicated?
A. Factor VIII deficiency
B. DIC
C. von Willebrand disease
D. Factor IX deficiency

Answer 15

C. von Willebrand disease

Question 16

Which results are associated with hemophilia A?
A. Prolonged APTT, normal PT
B. Prolonged PT and APTT
C. Prolonged PT, normal APTT
D. Normal PT and APTT

Answer 16

A. Prolonged APTT, normal PT

Question 17

Fibrin monomers are increased in which of the following conditions?
A. Primary fibrinolysis
B. DIC
C. Factor VIII deficiency
D. Fibrinogen deficiency

Answer 17

B. DIC

Question 18

Which of the following is associated with multiple factor deficiencies?
A. An inherited disorder of coagulation
B. Severe liver disease
C. Dysfibrinogenemia
D. Lupus anticoagulant

Answer 18

B. Severe liver disease

Question 19

Normal PT and APTT results in a patient with poor wound healing may be associated with:
A. Factor VII deficiency
B. Factor VIII deficiency
C. Factor XII deficiency
D. Factor XIII deficiency

Answer 19

D. Factor XIII deficiency

Question 20

Fletcher factor (prekallikrein) deficiency may be associated with:
A. Bleeding
B. Thrombosis
C. Thrombocytopenia
D. Thrombocytosis

Answer 20

B. Thrombosis

Question 21

One of the complications associated with a severe hemophilia A is:
A. Hemarthrosis
B. Mucous membrane bleeding
C. Mild bleeding during surgery
D. Immune-mediated thrombocytopenia

Answer 21

A. Hemarthrosis

In severe hemophilia A, factor VIII activity is less than 1%, resulting in a severe diathesis, such as hemarthrosis (bleeding into the joints.

Diathesis refers to the genetic, historical or biological vulnerabilities that can predispose an individual to certain mental health conditions when environmental stressors are also present. In medicine it means a tendency to suffer from a particular medical condition.

Question 22

The most common subtype of classic von Willebrand disease is:
A. Type 1
B. Type 2A
C. Type 2B
D. Type 3

Answer 22

A. Type 1

Question 23

Prolonged APTT and PT are corrected when mixed with normal plasma. Which factor is most likely deficient?
A. Factor VIII
B. Factor V
C. Factor XI
D. Factor IX

Answer 23

B. Factor V

Factor V (common pathway factor) deficiency is most likely suspected because both PT and APTT are prolonged, and both are corrected when mixed with normal plasma.